Landracing Forum
Tech Information => Technical Discussion => Topic started by: V4F STR 60 on December 18, 2014, 11:11:37 AM
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Well, the Montana Dodge Boys have decided to move ahead with building our V4F lakester for 2015. Fabrication starts early next year. I'm sure it's been tossed around here in forums before, but I can't seem to find any HARD DATA about rear axle and OD transmission parasitic losses. I'm not looking for, "I once read", or "Sparky Smith told me", or "In Australia"... because we all know pinions spin the opposite direction in the other hemisphere, right? :?
We do not spin our motor fast, so we need an extremely tall gear... taller than a 2.75. BUT, at some point we will be going to V4 and then blown V4 at which time we'll spin another 1000+ RPM. A blown XXO Chrysler will be on the horizon as well. I mention this because it means we might need ratios between 2.0 and 3.5 in the next 5 years.
We initially were looking at a Winter's Xtremeliner because of the available 2.0 and 3.08 Ring and Pinion options, but they're stupid expensive and way overkill for a V4F. The tech guy at Winters assured me that a V8 QC, even with the 3.78 R&P, would be more efficient than the Xtremeliner in our application.
We then thought about a Ford 9" like in our roadster, mostly because we already have ratios from 2.47 to 3.7, but from what I've read, 9" are awfully parasitic because of the low pinion position, and changing a pumpkin in a tank does not sound like much fun.
A salty veteran friend is hell bent on running an airshifted Liberty tranny with OD, but he must have more money than us.
I know Ford 8" are less parasitic than the 9" but we'd have to buy gears, and that doesn't address the issue of swapping it in a cramped tank.
I am leaning towards a Winter's V8 with 3.78 R&P, polished gears, and low drag seals & bearings.
So, here are the questions ~
1. Does a .8 OD tranny have more or less parasitic loss than a QC with a 3.78 R&P geared to a 2.5?
2. How much parasitic loss does the above QC have? DATA please.
3. How does the parasitic loss of the above QC compare to other rear axle options (other options must have a drop out pumpkin) DATA please.
Thanks for playing! See you on the SALT!
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According to these sources a Hypoid (most popular third members) gear set is 92 to 96 percent efficient at power transmission. A spiral bevel (V-8 quick change) gear set and a single spur gear set are both 99 percent efficient. That makes a V-8 quick change 98.01 percent efficient . Tell me again why I should dump my quick change.
http://www.zakgear.com/Hypoid_worm.html
http://www.roymech.co.uk/Useful_Tables/Drive/Gear_Efficiency.html
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7.5 2.14 2.28 2.56 2.73 2.92 3.08/ 3.08 3.23 3.42 3.73
8.5 2.41 2.56 2.73
10-12 8/78 (almost the same as Fords 8.8) 2.28 2.42 2.56 2.73 2.92 3.08
"The driving efficiency of an automotive hypoid gear is 92%-96%. Unfortunately the spiral bevel gear can not replace a hypoid gear in an automotive drive axle because it can not transmit as much of torque as a hypoid gear."
old Ford bevel gears are in the 98% range
GM axels are the 96%-95% range the 7.5 being more efficient
Ford 9" is in the 92%-91%
Virtually the only company still making car and light truck axels in the USA is American Axels-- spun of GM back in the 80-90s---the reason they are still around---better mileage in this day of mandated fuel economy because they are more EFFICIENT
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Pedro,
A timely post to be sure. The White Goose Bar roadster is stepping up to a Winters for next season. As a result there is a V8-QC available with so many gear sets I can't count. PM me if interested and I will put you in touch with Greg Waters.
Merry Christmas,
DW
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Doesn't the Nascar Cup cars use the 9 in?
Their fighting for every mph.
JL222
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Rules dictate everything used on a Cup car.
Pete
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I`d be more concerned with the gear reduction you will lose with an overdrive. Put a manual trans in 2nd gear and try to rotate it by the out-put shaft. See what I mean ??
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Unfortunately the spiral bevel gear can not replace a hypoid gear in an automotive drive axle because it can not transmit as much of torque as a hypoid gear.
It depends on how much torque you need to transmit
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I`d be more concerned with the gear reduction you will lose with an overdrive. Put a manual trans in 2nd gear and try to rotate it by the out-put shaft. See what I mean ??
Yep, going through an overdrive to get to an underdrive before you get to the wheel.
Sid.
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it is all just high school physics ---eng. Torque x T rans. R atio x R ear Axel ratio X T ire Correction = Tractive Effort
One is also dealing with the parasitic loss of each unit. The rule of thumb use to be 20% plus or minus for the whole drive train
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Sparky, how does the Mopar 8.75" compare with the Ford 9"? About the same?
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If it is a Dana it is in between the them and if it isn't is still is most likely between them
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When I saw the subject the first time I thought someone else lost his
rear axle to a "Parasite" too. :-D
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There ya go Bob, I recon Sparky just hooked you up with a definate maybe on that one. :-D
Sid.
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Hi to all: You guys keep throwing around percent this and percent that on gears, but have you ever seen them on a spin-tron machine or a chassis dyno? What is important and will tell you more is the coast down numbers they show. I have yet to see a quick change rear axle have better numbers, also how the gears are built and type of bearings used have a great influence on loss. I would find what ratios work and type you can afford then work from there. Our Ford 2:30 ratios set a number of records this year on the salt but some quickchange gears also set records so again work within your means and find the little things that will help. Hope all of you have a good X-Mas and New Year. Mike MF Performance
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:? :-). :-D :-D
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... Unfortunately the spiral bevel gear can not replace a hypoid gear in an automotive drive axle because it can not transmit as much of torque as a hypoid gear...
Only somewhat true. A bevel gear set would need to be slightly more robust for the same torque capacity as a hypoid set. The hypoid rear axles came into popular vehicle use when lower floorpans were desired (pinion shaft offset below axle centers).
Regarding the efficiency- note that straight-cut bevel gears are even more efficient than spiral bevel. Do any GC centers use straight-cut bevel ring & pinions?
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the QC based on early ford's banjo have bevel gears
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Unless you are running over 1100 Hp I would not even think about an Over Drive. (SoHK's)
Richard 2
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the QC based on early ford's banjo have bevel gears
The V-8 quick change has spiral bevel gears, I don't know about the model A type.
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. . . and then there's lubrication choices, too.
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. . . and then there's lubrication choices, too.
We've had good luck with the very light viscosity drag race axle and tranny lubes.
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0-20 synthetic eng oil in my rears
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0-20 synthetic eng oil in my rears
Sparky, you running polished gear set or not?
I have heard ... you know those people who say such things, to run the light oils you need a polished gear set.
Thanks,
Bill
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polished by miles and miles on American hwys.---I have never run anything but used gear sets
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Has anybody had bad experience from going out and running hard on new gears ? Are licensing runs enough to brake gears in ?
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Has anybody had bad experience from going out and running hard on new gears ? Are licensing runs enough to brake gears in ?
John this doesn't apply to you since you have no 'rear axle gears' :evil: :evil:. Sorry, couldn't resist.
Sparky was it you that said the guy who has set up your gears, sets the ring/pinion up a little looser than say he would for a street driven car that was going to go tens of thousands of mile on a new gear set? Maybe someone else told me or I'm tired and just imagined it or he said just the opposite :cry: :cry:,
Sumner
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Ranked by parasitic loss (lowest first):
Dana 60
Chrysler 8-3/4" (there are 3 pinion types)
Ford 9"
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Summ that was what I understood.
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Spur gears in a transmission have about 1% loss per mesh. The transmission has more losses than that due to oil churning some bearing losses etc. A straight bevel gear has about 1.5% loss. Hypoid and spiral bevel gears have much higher losses due to the fact that there is more sliding motion involved in the gear contact than you would with a straight bevel gear.
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Ranked by parasitic loss (lowest first):
Dana 60
Chrysler 8-3/4" (there are 3 pinion types)
Ford 9"
Pictured left to right in the 1st picture is Ford 9" 2.47, then Dana 44 2.72, then Dana Super 44 3.07....
These pics are not to discuss the parasitic loss directly, but for me to point out a few things I noticed and to ask a couple of questions:
The 2.72 standard Dana 44's splined portion is about 1/8" less OD than that of the Ford 9" 2.47. The Ford 9" 2.47 is about 1/16" less in OD than the Dana Super 44 in the Vipers. The Ford pinion has a nice conical step up to the larger diameter from the pinion spline whereas the 2.72 has a right angle step up which now explains why it breaks like glass when any kind of sticky tire gets traction on it as compared to the Super 44's 3.07 with which I have never heard of anybody having a problem.
The Ford's teeth on both the ring and pinion seem to be thicker and have more contact patch ie more drag as well as a more severe helical pitch which makes it seem to sit lower relative the ring gear than the Dana sets which I am sure also contributes to more drag/ drive line loss.
Now a question about the more obvious aspect of the Ford 2.47 which is the bearing support on the back side.... This setup with bearing support on both ends seems like it would allow the ring and pinion to maintain a tighter tolerance in relation to each other within the case which should track more consistently and be able to hold more power.
Any engineers or people who know more about this subject care to elaborate on anything else?
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(http://i742.photobucket.com/albums/xx66/ttviper1/019_zpsdb5c8f9e.jpg) (http://s742.photobucket.com/user/ttviper1/media/019_zpsdb5c8f9e.jpg.html)
(http://i742.photobucket.com/albums/xx66/ttviper1/020_zps4858fe36.jpg) (http://s742.photobucket.com/user/ttviper1/media/020_zps4858fe36.jpg.html)
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When you consider lubrication oils, Joe Gibbs products have served me well. They even list one for LSR. If you have room, dry sumping is another option. Also there were 3.27 and 3.54 ring and pinions sets for V8 QC's. Slowing the spur gears saves some HP. I have run Pontiacs for 39 years because of their pinion angle.
If you don't need a lot of trans gears there is a 2-speed which houses as set of QC gears on the back. You need to remove the drive shaft and rear trans plate to change them. A friend has 2 of them for sale. Good luck..JD